1. Field of the Invention
The invention describes a flexible polymer solid electrolyte that is useful in battery technology. The flexible polymer solid electrolyte comprises a first block, a second block comprising a polymer that incorporates ions of a first lithium salt within the microphase separated spherical domains of the polymer, and a second lithium salt.
2. Related Art
In recent years, interest in polymeric batteries has increased dramatically. Current configurations have a liquid or gel electrolyte along with a separator between the anode and cathode. This leads to problems with electrolyte loss and decreased performance over time. The highly reactive nature of such electrolytes necessitates the use of protective enclosures, which add to the size and bulk of the battery.
Polymer electrolytes are more compliant than conventional glass or ceramic electrolytes. Lightweight, shape-conforming, polymer electrolyte-based battery systems could find widespread application as energy sources in miniature medical devices such as pacemakers, wireless endoscopes, implantable pumps, treatment probes, and untethered robotic mobile manipulators.
The complex forming capability of poly(ethylene oxide) (PEO) with alkali metal salts, introduced by Fenton et al., Polymer 14:589 (1973), has been the starting point for an abundance of published work on polymer electrolytes for use in batteries. A semicrystalline polymer, PEO, has been a focal component in the design of numerous dry, solvent-free electrolytes involving blends (see Rajendran et al., J. Solid State Electrochem. 6:560 (2002)), block copolymers (see Gray et al., Macromolecules 21:392 (1988), Harris et al., Macromolecules 35:3772 (2002), Ryu et al., J. Electrochem. Soc. 152:A158 (2005), and Singh et al., Macromolecules 40:4578 (2007)), branched networks (see Kim et al., Polym. Eng. Sci. 34:1305 (1994)), ceramic fillers (see Croce et al., Nature 394:456 (1998), Croce et al., Electrochim. Acta 46:2457 (2001), Croce et al., J. Power Sources 162:685 (2006), and Kurian et al., Electrochim. Acta 50:2125 (2005)), room-temperature ionic liquids (see Seki et al., J. Phys. Chem. B 110:10228 (2006) and Shin et al., Electrochem. Commun. 5:1016 (2003)), and specialized salts (see Borghini et al., J. Electrochem. Soc. 142:2118 (1995) and Appetecchi et al., J. Electrochem. Soc. 148:A1171 (2001)). It is important to carefully tailor the polymer electrolyte matrix to attain appreciable levels of conductivity in a solid-state medium.
Thus, there is a need for a solid electrolyte that exhibits high ion transport at room temperature compared to traditional solid polymer electrolytes.